Cardiac diseases include heart failure, arrhythmia, myocardial infarction, angina, valvular heart disease and the like, and they are high-mortality diseases. In treatment of cardiac diseases with a drug, the symptoms are improved by control of each risk factor and symptomatic therapy. However, the satisfaction with treatment remains low level, and there is now no definitive therapy.
Calcium-calmodulin complex binds to Ca2+/calmodulin-dependent protein kinase (CaMK) included in serine/threonine protein kinase, and activates the kinase. The CaMK family includes CaMKII, and four isoforms (α, β, γ and δ) exist as CaMKII. CaMKII α and CaMKII β are expressed mainly in cerebral tissue, and CaMKII γ and CaMKII δ are expressed in many tissues including heart. CaMKII is activated by amino acid-modification due to oxidative stress or hyperglycemia, in addition to the binding of calcium-calmodulin complex. CaMKII regulates cell functions by phosphorylation of a transcription factor which is a substrate, a protein that plays a function in organelle uptake/excretion of Ca2+, a protein that regulates contract and relax of muscles, a channel that regulates an intracellular ion concentration, and the like, due to its kinase activation.
Some documents suggest that CaMKII plays a harmful role in progress of cardiac disease conditions. Expression and activity of CaMKII are increased in heart of human patient or animal with heart failure (Non-Patent Documents 1-4). In transgenic mouse overexpressing CaMKII δ in heart, onsets of cardiac hypertrophy and heart failure are reported (Non-Patent Document 4). By studies using an inhibitor by a pharmacological method, and studies using a gene deletion by genetic method, protecting effects on heart failure, cardiac hypertrophy, myocardial infarction and arrhythmia by an inhibition of CaMKII and an overexpression of CaMKII inhibitory protein are reported in mouse (Non-Patent Documents 5-7). For catecholaminergic polymorphic ventricular tachycardia, improving effects on disease conditions by CaMKII inhibitor in mutant ryanodine knock-in mouse (RyR2R4496C+/− mouse) are reported (Non-Patent Document 8). These findings suggest availabilities of CaMKII inhibitors in the prophylaxis and/or treatment of cardiac diseases including heart failure, cardiac hypertrophy, myocardial infarction and cardiac arrhythmia.
Recently, CaMKII exacerbating action on growth or metastasis of a certain type of cancer is suggested (Non-Patent Document 9). In addition, therapeutic effect on acute renal failure, intimal hypertrophy, hepatic fibrosis, stroke, pain, rheumatoid arthritis and the like by CaMKII inhibition are also indicated (Non-Patent Documents 10-15).
However, genetic methods achieve only deficiency of protein or overexpression of inhibitory protein, and they are different from a mechanism which inhibits temporarily kinase activity, and therefore, effects by kinase inhibitor cannot be always expected. In addition, inhibitors which have been already reported are not suitable for application as a medicament for a CaMKII selective inhibitor, because they have a low kinase selectivity to CaMKII, or they are not suitable for oral administration or chronic administration.
As a heterocyclic compound, the following compounds are known. Patent Document 1 describes that a compound represented by the following formula (I):

wherein each symbol is as defined in Patent Document 1, is a FLT3 inhibitor and useful for the treatment of acute myelogenous leukemia and the like.
Patent Document 2 describes that a compound represented by the following formula (I):
wherein each symbol is as defined in Patent Document 2, is a Syk (Spleen tyrosine kinase) inhibitor and useful for the treatment of diseases or conditions mediated by Syk (e.g., rheumatism).
Patent Document 3 describes that a compound represented by the following formula (I):
wherein each symbol is as defined in Patent Document 3, is a mGluR (metabotropic glutamate receptors) 5 modulator and useful for the treatment or prophylaxis of diseases or conditions in which mGluR5 is involved (e.g., pain disorder, anxiety, depression, Alzheimer's disease, Parkinson's disease, etc.).
Patent Document 4 describes that a compound represented by the following formula (I):
wherein each symbol is as defined in Patent Document 4, is a kinase inhibitor (particularly an inhibitor of kinase domain in VEGF receptor (VEGF receptor tyrosine kinase inhibitor)) and useful for the treatment of vascular abnormality, tumor, diabetic retinopathy, rheumatism, endometriosis, psoriasis and the like.
Patent Document 5 describes that a compound represented by the following formula (I):
wherein each symbol is as defined in Patent Document 5, is a kinase (p38 kinase, etc.) inhibitor and useful for reduction of ischemic cell death (particularly reduction of traumatic neuronalcell death).